Working apparatus for a limited area

Working apparatus for a limited working area, the apparatus comprising:

• a base station configured to generate a magnetic field extending at least in part over the working area;
• a self-propelling robot having a normal operating mode wherein it performs a working cycle in the working area and a base return mode wherein it returns automatically to the base station, the self-propelling robot comprising:
• means for moving the self-propelling robot in the working area, as a function of a movement driving signal;
• a gyroscope configured to generate an angular velocity signal indicating the measure of the angular velocity of the self-propelling robot around an axis substantially vertical with respect to the plane of the working area;
• a magnetic field sensor configured to generate a detection signal indicating a right or left position of the self-propelling robot with respect to a set of contiguous magnetic field lines of force;
• a processing unit configured to control the movement of the self-propelling robot inside the working area, the processing unit comprising:
• a magnetic field search module configured, during a magnetic field search phase of the base return mode, to generate, as a function of the values of the detection signal and of a traveled distance signal indicating the estimation of the distance traveled by the self-propelling robot, the movement driving signal for moving the self-propelling robot inside the working area to search for the set of contiguous magnetic field lines of force inside the working area according to a defined search path;
• a magnetic field tracking module configured, during a magnetic field tracking phase of the base return mode subsequent to the magnetic field search phase, to generate, as a function of the values of the detection signal, of the angular velocity signal and of the traveled distance signal, the movement driving signal for moving the self-propelling robot inside the working area to track at least a portion of the set of found contiguous lines of force by means of a plurality of maneuvers of crossing the set of found contiguous lines of force until reaching the base station.